This application claims the benefit of Korean Patent Application Serial No. 2001-8262, filed Feb. 19, 2001.
The present invention relates to a saw blade shank constituting the body of a diamond saw for cutting, for example, stones, with cutting tips provided on the circumference of the saw, and particularly to a saw blade shank which comprises two or more steel plates and a coated sheet having a plurality of electro-conductive points or multi-contact sheets inserted between the respective neighboring steel plates, to enhance the weldability and at the same time, to minimize the thermal deform or pressed marks, so that sound absorption, noise reduction and also heat dissipation may be maximized during a high speed cutting operation.
Generally, the diamond saw blade for cutting stones performs cutting operation at a rotation speed of several thousand revolutions per minute (r.p.m.). The vibration and noise from the friction and impact generated at that time can a cause of inadvertent accidents, which represents a major environmental disruption around working places. Further, heat is generated at the saw shanks during high speed cutting operation to cause a thermal deformation of the shanks, which results in the decreased cutting efficiency and possibly safety problem due to wobble of shank.
To solve such a problem, from Korean unexamined patent publication No. 10-2000-0025865 there was known a saw blade shank consisting of two steel plates, between which an alloy sheet made of aluminum, nickel, copper or the like is fitted to reduce vibration and noise. However, this type of shanks is limited because of the difficulty in the manufacture and the high production cost.
Moreover, Korean unexamined patent publication No. 10-2000-005487 describes a method for manufacturing a sandwiched panel type circular saw blade shank of non-metal or plastic by using projection welding. In further particular, steel balls as fusible material are placed in the holes formed between parallel plastic plates and then electric current is supplied to the upper and lower electrodes with a compressive force applied to fuse the balls, whereby a low-noise saw blade shank is made. This method is, however, disadvantageous in that a fully appropriate joining strength is not often attained because the fusible material is not uniformly fused over the whole surface of a shank due to the variance in the characteristics of the supplied electric current caused by the possible size difference in the balls.
There is disclosed a still other technology, for example, in the Korean unexamined patent publication No. 10-1998-032841 and U.S. Pat. No. 5,078,035, in which holes with various shapes are formed on an ordinary saw blade shank to help dissipate the heat generated in cutting work and also to reduce the vibration of a saw. This method is also associated with the drawback on the ground that the holes are formed throughout the thickness of one sheet of shank and therefore the mechanical strength of the saw shank is so reduced as to cause the deformation of the shank by the mechanical load, beside the deformation due to thermal load, during a cutting operation. In addition, the dust or sludge generated during the cutting operation can scatter through the holes on shanks and harm the respiratory organs of workers, not to mention polluting the working sites.
In order to resolve the problem just described, the Japanese unexamined patent publication Hei 10-286775 describes an arrangement consisting of three or more plates including intermediate steel layers with the layer thickness of about 0.2 to 0.7 mm and having through-holes, the three or more plates being joined by spot welding. While the holes in the intermediate layer are intended to function as an absorber of the dust and noise and as a heat dissipater, the steel substrate of the shank is not so high in the heat conductivity and the effect of damping noise by the holes is not so excellent as well.
The present invention is to resolve the problems with the conventional art as described above and the object of the invention is to improve the conventional saw blade shank of sandwiched type by providing, as the intermediate layer, a coated thin sheet with a plurality of electro-conductive points or a thin sheet with multiple contacts to enhance weldability and to minimize the thermal deform or pressed marks, so that sound absorption, noise reduction and also heat dissipation may be maximized during a high speed cutting operation.
The object as described above is achieved according to an aspect of the invention by a saw blade shank with cutting tips on the circumference of the shank, comprising two or more conductive steel plates and a coated thin sheet as a intermediate layer inserted between the neighboring conductive steel plates, the coated thin sheet being coated so as to leave a plurality of uncoated areas on at least one of its surfaces, whereby the coated thin sheet and the steel plates (22,24) are integrally combined by multi-contact thermal fusion through a predetermined high pressure and electric current concentrated on the uncoated areas.
The object as described above is also achieved according to another aspect of the invention by a saw blade shank with cutting tips on the circumference of the shank, comprising two or more conductive steel plates and multi-contact thin sheets each having plural projections on one or both sides of the thin sheet, inserted between the neighboring steel plates, whereby the multi-contact thin sheets and the steel plates are integrally combined by multi-contact thermal fusion through a predetermined high pressure and electric current concentrated on the plural projections.